chore: stop tracking .env and ignore it

.env holds credentials (API_DOC_PASSWORD, secrets) and must not be in git.
Removed it from tracking (file kept on disk) and added .env to .gitignore.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -54,4 +54,5 @@ npm-debug.log
 yarn-error.log
 ###< symfony/webpack-encore-bundle ###
 clinicpro/*
-clinicpromain/*
+clinicpromain/*
+.env